This article reviews major risk factors for cigarette smoking, alcohol, and other drug abuse and promising community-based approaches to primary prevention. In a longitudinal experimental study, 8 representative Kansas City communities were assigned randomly to program (school, parent, mass media, and community organization) and control (mass media and community organization only) conditions. Programs were delivered at either 6th or 7th grade, and panels were followed through Grade 9 or 10. The primary findings were (a) significant reductions at 3 years in tobacco and marijuana use and (b) equivalent reductions for youth at different levels of risk. This study provides evidence that a comprehensive community program-based approach can prevent the onset of substance abuse and that the benefits are experienced equally by youth at high and low risk.